CPT Theorem

The CPT theorem, one of the most basic assertions of physics, arises from the success of quantum field theories. Quantum field theories seem to provide a very successful description of all interactions except for gravitational interactions. Where a quantum field theory is a correct description, along with the usual assumptions such as invariance under Lorentz transformations, the necessary result is that the reality that is described is invariant under a CPT transformation. This is called the CPT theorem. However, since gravity has not yet been successfully described by a quantum field theory, it is possible that the CPT is not universal. The only way to tell is to look.

CPT invariance implies that particles and antiparticles have the same:

mass

charge-to-mass (except opposite sign)

magnetic moment (except opposite sign)

mean life

atomic structure

Testing to see whether particles and antiparticles have properties related in this way is thus a test of CPT invariance.